Replacing seals in hydraulic cylinders - jacks, hoists, presses

Once upon a time... The equipment mfgrs were in U.S. and there products had I.D. tags. They were the source for repair parts too. In most cases the seals, bearings, etc.., were industrial standard dimensions, inch standard too, so a local vendor could very well have the same parts.
Largest exception was appliance mfgrs., especially washing machines. They very often had non standard parts produced so they were the only source for replacement parts.
Today... Everything is made in a land far far away... no brand name, no idea who to contact.
The D.I.N. standards adopted in early 80s helped get much of what they make and what is made everywhere else to the same industrial standards. Mostly metric dimensions though.
The end user can only gamble. Take the assembly apart, try to source parts, get lucky or loose. I've lost a few times. Found I had wasted my time. My final thought, "It would have been easier tossed in the dumpster if I hadn't taken it apart first". Good luck